feat(launcher): Linux AppImage 1.0.2, Gitea sync + CI, manual pack script

- Add pack:linux (AppImage x64), linux/appImage artifact names in package.json.
- Gitea sync: parallel build-electron-linux, merge Windows+Linux into Gitea upload;
  rename Windows artifact to electron-dist-windows.
- Fractured launcher CI: electron-launcher-windows + electron-launcher-linux jobs.
- scripts/manual-pack-linux.sh for local test builds from current tree.
- Normalize Gitea base_url (prepend https if missing); baked channel uses full URL.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/fractured-launcher-ci.yml

@@ -22,7 +22,7 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  electron-launcher:
+  electron-launcher-windows:
     runs-on: windows-latest
     timeout-minutes: 45
     defaults:
@@ -50,3 +50,32 @@ jobs:
             tools/fractured-launcher-electron/dist/*.exe
             tools/fractured-launcher-electron/dist/latest.yml
             tools/fractured-launcher-electron/dist/*.blockmap
+
+  electron-launcher-linux:
+    runs-on: ubuntu-latest
+    timeout-minutes: 45
+    defaults:
+      run:
+        working-directory: tools/fractured-launcher-electron
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: npm
+          cache-dependency-path: tools/fractured-launcher-electron/package-lock.json
+
+      - name: Install and pack (AppImage)
+        run: |
+          npm ci
+          npm run pack:linux
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: fractured-launcher-electron-linux-${{ github.run_id }}
+          if-no-files-found: warn
+          path: |
+            tools/fractured-launcher-electron/dist/*.AppImage
+            tools/fractured-launcher-electron/dist/*.yml
+            tools/fractured-launcher-electron/dist/*.blockmap